Durum wheat (the tetraploid wheat Triticum turgidum L. var. durum, synonym T. durum) is one of the most important cereal crops in the world. Also known as “hard” wheat or macaroni wheat, it is cultivated in semiarid regions of the world such as North Africa, Mediterranean Europe, the North American Great Plains and the Middle East. Its kernel size, hardness and golden amber color make it most suitable for manufacturing a unique and diverse range of food products. Pasta and couscous are the most common paste products made from durum wheat.
Durum wheat also can be used for making bread, however, bread wheat (the hexaploid wheat T. aestivum) is the main source of flour for making bread. Generally bread wheat is not used to manufacture pasta or couscous.
Wheat belongs to the genus Triticum, all members of which contain a multiple of the basic haploid set of seven chromosomes (x=7). The wheats form an all polyploid series with diploid (2n=2x=14), tetraploid (2n=4x=28), and hexaploid (2n=6x=42) species. Within each species, chromosomes pair in a diploid-like fashion, and the mode of inheritance is disomic.
Cytogenetic, biochemical, morphological and genetic analyses have been used to assess the evolutionary development of the cultivated tetraploid and hexaploid wheat. The designated A-genome is derived from the diploid T. monococcum L. (synonyms T. boeoticum and T. urartu). T. monococcum was long considered the A-genome donor. At the wild tetraploid level, T. dicocoides (AABB) may have the A-genome from T. monococcum and the B-genome of T. speltoides (Tausch) Gren. Ex Richter, synonym Aegilops speltoides. Common bread wheat, the hexaploid T. aestivum (AABBDD) has the A- and B-genomes of a tetraploid T. turgidum and the D-genome derived from T. taushii (Coss.) Schmal., synonym Aegilops sqarrosa. The two species T. turgidum L. var. dicoccoides and Aegilops sqaurrosa are considered the nearest wild progenitors of common bread wheat. T. dicoccoides is the only wild member of the wheat group fully interfertile with cultivated T. turgidum L var. durum. 
The tetraploid emmer wheats T. dicoccum shrank, T. dicoccoides, and T. turgidum L var. durum also can be crossed directly with hexaploid wheats. The F1 generation may exhibit a high degree of sterility, but seed set can be obtained.
Fusarium head blight (FHB) is caused by the fungus Fusarium, typically F. graminearum Schwabe (telomorph Gibberella zea (Schwein.) Petch) but other causal agents can include F. culmorum and F. avenaceum. Fusarium head blight is a serious threat to durum wheat. Since 1993, it is estimated that Fusarium head blight has cost over $3 billion in direct and indirect losses in North Dakota (Sayler, Scab on rampage: where do we go from here? Prairie Grains, November/December, issue 10 pp 14, 19-21, 35 and 39 (1997)). Fusarium head blight not only reduces yield but also reduces the quality of the end products of durum wheat (Dexter et al., Cereal Chem., 74:519 (1997)). The fungus is also associated with mycotoxins, particularly trichothecene deoxynivalenol (DON vomitoxin), that are hazardous to humans and other animals.
There is a continuous decline in harvested durum acreage and production in North Dakota because of Fusarium head blight. The harvested acreage in North Dakota in 2001 was 2.25 million acres. This acreage is 22% less than the year 2000 (State of North Dakota, Agriculture Statistics). In 2001 North Dakota produced 60.75 million bushels of durum wheat, which was a 22% decrease in production as compared to production in the year 2000 (National Agriculture Statistics, 2001). The decline in harvested acreage and durum production in North Dakota is disastrous to the farm economy and has direct impact on the national pasta industry. In addition, the international export market is also greatly affected since North Dakota on average produces 75% of the durum in the United States.
Fungicides can be used to improve yield and other agronomic traits but the level of improvement is below the margin of the economic return (McMullen, Evaluation of fungicides for suppression of Fusarium head blight. in Current research on Fusarium head blight of small grains, November (1997) NDSU research publication, Fargo, N.Dak. (1997)). Although fungicides may reduce Fusarium head blight, the use of genetic resistance is the most environmentally safe and economical way to control the disease. Durum wheat with appropriate combinations of resistant genes could effectively control the disease. Accordingly, what is needed is the development of wheat, particularly durum wheat, that is genetically resistant to Fusarium. 